OpenEuphoria

1. Hexadecimal numbers in Eu

• Posted by "Juergen Luethje" <j.lue at gmx.de> Sep 16, 2004
• 446 views

Hi,

in some other programming languages, hex numbers can represent positive
or negative values. E.g. in PowerBASIC 3.2,
   ? &hFFF0       ' prints -16
   ? &h00F0       ' prints 240

>From what I read at 'refman_2.htm#1' (Eu 2.4), and from my experience,
I have the impression that hexadecimal numbers (that don't have a '-'
sign at the beginning) in Euphoria _always_ have positive values.

Rob, is this true?

In Euphoria, e.g.

? #FFF0       -- prints 65520
   ? #00F0       -- prints 240

Regards,
   Juergen

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3. Re: Hexadecimal numbers in Eu

• Posted by "Juergen Luethje" <j.lue at gmx.de> Sep 16, 2004
• 464 views

Derek Parnell wrote:

> Juergen Luethje wrote:
>>
>> Hi,
>>
>> in some other programming languages, hex numbers can represent positive
>> or negative values. E.g. in PowerBASIC 3.2,
>>    ? &hFFF0       ' prints -16
>>    ? &h00F0       ' prints 240
>>
>>> From what I read at 'refman_2.htm#1' (Eu 2.4), and from my experience,
>> I have the impression that hexadecimal numbers (that don't have a '-'
>> sign at the beginning) in Euphoria _always_ have positive values.
>>
>> Rob, is this true?
>>
>> In Euphoria, e.g.
>> }}}
<eucode>
>>    ? #FFF0       -- prints 65520
>>    ? #00F0       -- prints 240
>> </eucode>
{{{

>
>
> Yes, hexadecimal literals are always positive unless they have a leading
> minus symbol.

Rob, maybe this sentence could be added to the docs? I think it will be
very helpful for beginners -- and people like me, who sometimes feel
like beginners. 

[[Grrmmpf.. "leading". That is the word I was searching for, in any
corner of my brain, and didn't find it. ]]

> However it is a bit confusing because negative integers, when converted
> to display as hex digits via the printf() routine, display without
> the minus sign.
>
> printf(1, "%x", -1)  --> FFFFFFFF

Yes, this actually confused me some days ago!! Thanks, Derek!

Rob, is there any chance that in a future version of Euphoria,
   printf(1, "%x", -1)
will show '-1' or '-#1' instead of 'FFFFFFFF'?

Regards,
   Juergen

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5. Re: Hexadecimal numbers in Eu

• Posted by "Juergen Luethje" <j.lue at gmx.de> Sep 18, 2004
• 433 views

D L wrote:

> It is just a matter of interpretation.
> Do you use 00000000-FFFFFFFF as an all positive range, or split it halfway to
> have positive and negative values?.
>
> The halfway is the tricky part, because it does not follow the "normal"
> decimal sequence, i.e. start at the most negative, thru zero and on to the most
> positive.
>
> You start at 0 dec/hex, go up to the largest positive (7F FF FF FF) and then
> continue counting from the most negative (80 00 00 00) up to -1 dec/FF FF FF FF
> hex.
>
> To get negative decimal values test hex, if it is #80 00 00 00 or larger then
> use formula:
> negative decimal=-(not_bits(hex)+1)
>
> All assuming hex is represented using 4 bytes (note: print %x seems to set the
> limit at 4 bytes).

I wrote something similar one week or so ago in a different thread ...

What question are you trying to answer here?
I can't even see to which post you are replying, neither formally nor
regarding the content. When you reply to a post, please quote the text
that you are referring to. For details e.g. see here:
http://www.netmeister.org/news/learn2quote.html

My first question in this thread has already been answered by Derek.
Then I asked Rob two additional questions. He didn't reply until now,
however, I don't think that anyone else can answer the questions.

Regards,
   Juergen

-- 
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7. Re: Hexadecimal numbers in Eu

• Posted by "Juergen Luethje" <j.lue at gmx.de> Sep 19, 2004
• 472 views

Robert Craig wrote:

> Juergen Luethje wrote:
>>
>> Derek Parnell wrote:
>>
>>> Juergen Luethje wrote:
>>>>
>>>> Hi,
>>>>
>>>> in some other programming languages, hex numbers can represent positive
>>>> or negative values. E.g. in PowerBASIC 3.2,
>>>>    ? &hFFF0       ' prints -16
>>>>    ? &h00F0       ' prints 240
>>>>
>>>>> From what I read at 'refman_2.htm#1' (Eu 2.4), and from my experience,
>>>> I have the impression that hexadecimal numbers (that don't have a '-'
>>>> sign at the beginning) in Euphoria _always_ have positive values.
>>>>
>>>> Rob, is this true?
>>>>
>>>> In Euphoria, e.g.
>>>> }}}
<eucode>
>>>>    ? #FFF0       -- prints 65520
>>>>    ? #00F0       -- prints 240
>>>> </eucode>
{{{

>>>
>>>
>>> Yes, hexadecimal literals are always positive unless they have a leading
>>> minus symbol.
>>
>> Rob, maybe this sentence could be added to the docs? I think it will be
>> very helpful for beginners -- and people like me, who sometimes feel
>> like beginners. 
>
> OK, I'll say something in the docs about this.

Thanks, that will eliminate ambiguity.

>>> However it is a bit confusing because negative integers, when converted
>>> to display as hex digits via the printf() routine, display without
>>> the minus sign.
>>>
>>> printf(1, "%x", -1)  --> FFFFFFFF
>>
>> Yes, this actually confused me some days ago!! Thanks, Derek!
>>
>> Rob, is there any chance that in a future version of Euphoria,
>>    printf(1, "%x", -1)
>> will show '-1' or '-#1' instead of 'FFFFFFFF'?
>
> Euphoria's %x format for printf() uses C's %x format,
> and only works for numbers up to 32-bits in size.
> }}}
<eucode>
>      printf(1, "%x", #FFFFFFFF)
> </eucode>
{{{

> displays FFFFFFFF
> as does:
> }}}
<eucode>
>      printf(1, "%x", -1)
> </eucode>
{{{

> but Euphoria does *not* consider #FFFFFFFF to be equal to -1.

Either it should do so, or

printf(1, "%x", -1)

should *not* display FFFFFFFF!!
This is a great inconsistency, and a source for confusion (as Derek
wrote, too) and bugs.

> When people are printing numbers with %x format
> they usually want to see -1 displayed as FFFFFFFF,

It depends. E.g. people who are new to programming probably would not
expect anything, because it will be the first time they deal with hex
numbers, and they just learn what they see.

I agree that more experienced programmers, printing numbers with %x
format, probably want to see -1 displayed as FFFFFFFF. But this people
probably also want Euphoria to consider #FFFFFFFF to be equal to -1!

So most important IMHO: Neither newbies nor 'oldbies' do like
inconsistencies! Especially not in a programming language, which is for
them a tool that should help them to perform *logical* operations.

include get.e

type int_32bit (object x)
   -- 32-bit integer (signed or unsigned)

   if atom(x) then
      if x = floor(x)
      and -#80000000 <= x and x <= #FFFFFFFF then
         return 1
      end if
   end if
   return 0
end type

function xconvert (int_32bit a)
   sequence ret

   ret = value(sprintf("#%x", a))
   if ret[1] != GET_SUCCESS then
      puts(1, "Error concerning value(), program terminated!")
      abort(1)
   end if
   return ret[2]
end function

int_32bit a, v

a = -1

puts(1, "Handling of hexadecimal numbers (Eu 2.4):\n")
v = xconvert(a)
if v = a then
   printf(1, "%d = %d\n", {v, a})
   puts(1, "consistent behaviour ")
else
   printf(1, "%d != %d\n", {v, a})
   puts(1, "inconsistent behaviour ")
end if

For any negative value of 'a', this test will show inconsistent
behaviour. Except of backward compatibility, I can't see any reason why
this behaviour should be maintained.

> so I don't plan to change it.



> Just as people have made their own versions of pretty_print(),
> there's no reason someone couldn't make an enhanced version
> of printf(), with lots of fancy new % formats. Very few programs
> require a really fast printf().

I know, but that was not my point. Newbies are probably not able to make
their own version of printf(). Also, I (and other people, too) want
their Eu code to be compatible with the rest of the Eu world.

What I wrote was neither a request for a feature that I just want
privately, nor a wish for a "fancy new % format", but a serious
suggestion for improvement of Euphoria in general. If you don't want to
implement it, I'll accept it. But please recognize the difference.

Regards,
   Juergen

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9. Re: Hexadecimal numbers in Eu

• Posted by "Juergen Luethje" <j.lue at gmx.de> Sep 19, 2004
• 418 views
• Last edited Sep 20, 2004

Derek Parnell wrote:

> Juergen Luethje wrote:
>>
>> Robert Craig wrote:

<big snip>

>>> When people are printing numbers with %x format
>>> they usually want to see -1 displayed as FFFFFFFF,
>>
>> It depends. E.g. people who are new to programming probably would not
>> expect anything, because it will be the first time they deal with hex
>> numbers, and they just learn what they see.
>
>
> I'll interject just here because we probably should understand the
> purpose of %x. My understanding is it is used to display the bit pattern
> of the integer, as it is represented in RAM. And thus -1 should be
> output as FFFFFFFF because that is how -1 is represented as a 32-bit
> value.

Aaaah!

> I agree it is confusing if you don't know that's what %x is trying to
> do.
>
>> I agree that more experienced programmers, printing numbers with %x
>> format, probably want to see -1 displayed as FFFFFFFF. But this people
>> probably also want Euphoria to consider #FFFFFFFF to be equal to -1!
>
> The difference between #FFFFFFFF and the output of %x is that the first
> is a literal coded into the source code, and such literals are always
> positive integers. And the second is bit pattern display of the integer
> in RAM.
>
> If you want to use negative hexadecimal literals you just place a '-'
> in front of the literal.
>
> atom test
> test = -#1
> test = -#FFFF
>
> If you want to display the value (rather than the bit pattern) of an
> integer in hexadecimal format try this ...
>
> if test < 0 then
>   printf(1, "-%x, ", -test)
> else
>   printf(1, "%x, ", test)
> end if

I think, I understand now. Thanks a lot for the comprehensive
explanation, Derek!

Regards,
   Juergen

11. Re: Hexadecimal numbers in Eu

• Posted by Derek Parnell <ddparnell at bigpond.com> Sep 19, 2004
• 443 views
• Last edited Sep 20, 2004

D L wrote:

[snip]

> refman2 says: Atoms can have any integer or double-precision floating point
> value. They can range from approximately -1e300 (minus one times 10 to the
> power 300) to +1e300 with 15 decimal digits of accuracy...
> Numbers can also be entered in hexadecimal...
> 
> Maybe Rob can give more details on how numbers are stored.

>From memory, integers are stored as 30-bit values plus a 1-bit sign flag.
Atom are IEEE 64-bit floating point values.

-- 
Derek Parnell
Melbourne, Australia

13. Re: Hexadecimal numbers in Eu

• Posted by "Unkmar" <L3Euphoria at bellsouth.net> Sep 20, 2004
• 443 views

----- Original Message -----
From: "Derek Parnell" <guest at RapidEuphoria.com>
To: <EUforum at topica.com>
Sent: Sunday, September 19, 2004 10:42 AM
Subject: Re: Hexadecimal numbers in Eu


>
>
> posted by: Derek Parnell <ddparnell at bigpond.com>
>
> Juergen Luethje wrote:
> >
> > Robert Craig wrote:
> >
> > > Juergen Luethje wrote:
> > >>
> > >> Derek Parnell wrote:
> > >>
> > >>> Juergen Luethje wrote:
> > >>>>
> > >>>> Hi,
> > >>>>
> > >>>> in some other programming languages, hex numbers can represent
positive
> > >>>> or negative values. E.g. in PowerBASIC 3.2,
> > >>>>    ? &hFFF0       ' prints -16
> > >>>>    ? &h00F0       ' prints 240
> > >>>>
> > >>>>> From what I read at 'refman_2.htm#1' (Eu 2.4), and from my
experience,
> > >>>> I have the impression that hexadecimal numbers (that don't have a
'-'
> > >>>> sign at the beginning) in Euphoria _always_ have positive values.
> > >>>>
> > >>>> Rob, is this true?
> > >>>>
> > >>>> In Euphoria, e.g.
> > >>>> }}}
<eucode>
> > >>>>    ? #FFF0       -- prints 65520
> > >>>>    ? #00F0       -- prints 240
> > >>>> </eucode>
{{{

> > >>>
> > >>>
> > >>> Yes, hexadecimal literals are always positive unless they have a
leading
> > >>> minus symbol.
> > >>
> > >> Rob, maybe this sentence could be added to the docs? I think it will
be
> > >> very helpful for beginners -- and people like me, who sometimes feel
> > >> like beginners. 
> > >
> > > OK, I'll say something in the docs about this.
> >
> > Thanks, that will eliminate ambiguity.
> >
> > >>> However it is a bit confusing because negative integers, when
converted
> > >>> to display as hex digits via the printf() routine, display without
> > >>> the minus sign.
> > >>>
> > >>> printf(1, "%x", -1)  --> FFFFFFFF
> > >>
> > >> Yes, this actually confused me some days ago!! Thanks, Derek!
> > >>
> > >> Rob, is there any chance that in a future version of Euphoria,
> > >>    printf(1, "%x", -1)
> > >> will show '-1' or '-#1' instead of 'FFFFFFFF'?
> > >
> > > Euphoria's %x format for printf() uses C's %x format,
> > > and only works for numbers up to 32-bits in size.
> > > }}}
<eucode>
> > >      printf(1, "%x", #FFFFFFFF)
> > > </eucode>
{{{

> > > displays FFFFFFFF
> > > as does:
> > > }}}
<eucode>
> > >      printf(1, "%x", -1)
> > > </eucode>
{{{

> > > but Euphoria does *not* consider #FFFFFFFF to be equal to -1.
> >
> > Either it should do so, or
> > }}}
<eucode>
> >    printf(1, "%x", -1)
> > </eucode>
{{{

> > should *not* display FFFFFFFF!!
> > This is a great inconsistency, and a source for confusion (as Derek
> > wrote, too) and bugs.
> >
> > > When people are printing numbers with %x format
> > > they usually want to see -1 displayed as FFFFFFFF,
> >
> > It depends. E.g. people who are new to programming probably would not
> > expect anything, because it will be the first time they deal with hex
> > numbers, and they just learn what they see.
>
>
> I'll interject just here because we probably should understand the
> purpose of %x. My understanding is it is used to display the bit pattern
> of the integer, as it is represented in RAM. And thus -1 should be
> output as FFFFFFFF because that is how -1 is represented as a 32-bit
> value.
>
> I agree it is confusing if you don't know that's what %x is trying to
> do.
>
> > I agree that more experienced programmers, printing numbers with %x
> > format, probably want to see -1 displayed as FFFFFFFF. But this people
> > probably also want Euphoria to consider #FFFFFFFF to be equal to -1!
>
> The difference between #FFFFFFFF and the output of %x is that the first
> is a literal coded into the source code, and such literals are always
> positive integers. And the second is bit pattern display of the integer
> in RAM.
>
> If you want to use negative hexadecimal literals you just place a '-'
> in front of the literal.
>
> atom test
> test = -#1
> test = -#FFFF
>
> If you want to display the value (rather than the bit pattern) of an
> integer in hexadecimal format try this ...
>
> if test < 0 then
>   printf(1, "-%x, ", -test)
> else
>   printf(1, "%x, ", test)
> end if
>
> --
> Derek Parnell
> Melbourne, Australia


Yeah, what Derek said.

    unkmar

15. Re: Hexadecimal numbers in Eu

• Posted by "Kat" <gertie at visionsix.com> Sep 20, 2004
• 435 views

On 20 Sep 2004, at 9:04, cklester wrote:

<snip>

?! sheesh.

no

Kat

17. Re: Hexadecimal numbers in Eu

• Posted by CoJaBo <cojabo at suscom.net> Sep 20, 2004
• 453 views
• Last edited Sep 21, 2004

cklester wrote:
> 
> Unkmar wrote:
> > 
> > ----- Original Message -----
> > From: "Derek Parnell" <guest at RapidEuphoria.com>
> > To: <EUforum at topica.com>
> > Sent: Sunday, September 19, 2004 10:42 AM
> > Subject: Re: Hexadecimal numbers in Eu
> > 
> > 
> > > posted by: Derek Parnell <ddparnell at bigpond.com>
> > >
> > > Juergen Luethje wrote:
> > > >
> > > > Robert Craig wrote:
> > > >
> > > > > Juergen Luethje wrote:
> > > > >>
> > > > >> Derek Parnell wrote:
> > > > >>
> > > > >>> Juergen Luethje wrote:
> > > > >>>>
> > > > >>>> Hi,
> > > > >>>>
> > > > >>>> in some other programming languages, hex numbers can represent
> > positive
> > > > >>>> or negative values. E.g. in PowerBASIC 3.2,
> > > > >>>>    ? &hFFF0       ' prints -16
> > > > >>>>    ? &h00F0       ' prints 240
> > > > >>>>
> > > > >>>>> From what I read at 'refman_2.htm#1' (Eu 2.4), and from my
> > experience,
> > > > >>>> I have the impression that hexadecimal numbers (that don't have a
> > '-'
> > > > >>>> sign at the beginning) in Euphoria _always_ have positive values.
> > > > >>>>
> > > > >>>> Rob, is this true?
> > > > >>>>
> > > > >>>> In Euphoria, e.g.
> > > > >>>> }}}
<eucode>
> > > > >>>>    ? #FFF0       -- prints 65520
> > > > >>>>    ? #00F0       -- prints 240
> > > > >>>> </eucode>
{{{

> > > > >>>
> > > > >>>
> > > > >>> Yes, hexadecimal literals are always positive unless they have a
> > leading
> > > > >>> minus symbol.
> > > > >>
> > > > >> Rob, maybe this sentence could be added to the docs? I think it will
> > be
> > > > >> very helpful for beginners -- and people like me, who sometimes feel
> > > > >> like beginners. 
> > > > >
> > > > > OK, I'll say something in the docs about this.
> > > >
> > > > Thanks, that will eliminate ambiguity.
> > > >
> > > > >>> However it is a bit confusing because negative integers, when
> > converted
> > > > >>> to display as hex digits via the printf() routine, display without
> > > > >>> the minus sign.
> > > > >>>
> > > > >>> printf(1, "%x", -1)  --> FFFFFFFF
> > > > >>
> > > > >> Yes, this actually confused me some days ago!! Thanks, Derek!
> > > > >>
> > > > >> Rob, is there any chance that in a future version of Euphoria,
> > > > >>    printf(1, "%x", -1)
> > > > >> will show '-1' or '-#1' instead of 'FFFFFFFF'?
> > > > >
> > > > > Euphoria's %x format for printf() uses C's %x format,
> > > > > and only works for numbers up to 32-bits in size.
> > > > > }}}
<eucode>
> > > > >      printf(1, "%x", #FFFFFFFF)
> > > > > </eucode>
{{{

> > > > > displays FFFFFFFF
> > > > > as does:
> > > > > }}}
<eucode>
> > > > >      printf(1, "%x", -1)
> > > > > </eucode>
{{{

> > > > > but Euphoria does *not* consider #FFFFFFFF to be equal to -1.
> > > >
> > > > Either it should do so, or
> > > > }}}
<eucode>
> > > >    printf(1, "%x", -1)
> > > > </eucode>
{{{

> > > > should *not* display FFFFFFFF!!
> > > > This is a great inconsistency, and a source for confusion (as Derek
> > > > wrote, too) and bugs.
> > > >
> > > > > When people are printing numbers with %x format
> > > > > they usually want to see -1 displayed as FFFFFFFF,
> > > >
> > > > It depends. E.g. people who are new to programming probably would not
> > > > expect anything, because it will be the first time they deal with hex
> > > > numbers, and they just learn what they see.
> > >
> > >
> > > I'll interject just here because we probably should understand the
<snip>


> 
> -=ck
> "Programming in a state of EUPHORIA."
> <a
> href="http://www.cklester.com/euphoria/">http://www.cklester.com/euphoria/</a>
>